Is safe, green thorium power finally ready for prime time?

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If you’ve not been tracking the thorium hype, you might be interested to learn that the benefits liquid fluoride thorium reactors (LFTRs) have over light water uranium reactors (LWRs) are compelling. Alvin Weinberg, who invented both, favored the LFTR for civilian power since its failures (when they happened) were considerably less dramatic — a catastrophic depressurization of radioactive steam, like occurred at Chernobyl in 1986, simply wouldn’t be possible. Since the technical hurdles to building LFTRs and handling their byproducts are in theory no more challenging, one might ask — where are they?

The enrichment of natural uranium is the first and perhaps most difficult step to building nuclear weapons. LWRs, which by their nature require enriched uranium, were the logical choice at the dawn of the nuclear age to develop an industry around. Richard Martin, a writer for Wired and author of Superfuel: Thorium, the Green Energy Source for the Future, summarized the argument a little more succinctly: the US abandoned thorium reactors because they didn’t produce plutonium bombs. The larger truth, of course, is a little more complex.

Today’s nuclear industry might be described as an elephant. It would be very difficult for an elephant to evolve wings (thorium) because big animals just do not evolve wings — little animals evolve wings and they in turn might evolve into bigger animals with wings. The chosen gimmick of the proto-elephant was the trunk (uranium), at first just a little one, but as elephants got larger, their trunks got really really large; it became their defining feature.

The molten salt reactor (MSR), predecessor of the LFTR, lost out to the LWR in the early ’50s for a simple reason. When Navy Admiral Hyman Rickover got wind of the possibilities of nuclear power, he wanted and got nuclear-powered submarines. Unfortunately for the MSR, sodium would react violently if it accidentally contacted water. The baby nuclear elephant would be a small machine, but light water uranium reactors, which already had a little head start, would be the technology. It also didn’t help the case for MSRs that naval and shipyard engineers were already the best in the world at working with water. They were experts at building the corrosion resistant pumps, valves, bearings and other machinery needed to utilize it. But as Martin keenly observes in Superfuel, five decades later we see that the essential element of today’s technology, pressurized water, has become its Achilles heal.

Weinberg continued to pour his efforts into a small, workable MSR to be used as a powerplant for a nuclear airplane. This was an unfortunate misdirection. In a time when there were actual plans to use nuclear technology to dam the Straight of Gibraltar and reclaim lands long ago submerged under the Mediterranean, the idea of a nuclear airplane was not so absurd. The Cold War not withstanding, in times of prevailing peace, a flying nuclear reactor cannot count its first success as managing not to crash and destroy itself. The US and Russia ran similar programs and flew test reactors on board conventional aircraft, but ultimately both projects were scrapped.

Many people think it is not too late today, to attempt put some muscle into Dumbo’s ears so to speak, and revisit the thorium reactor. Several private efforts in the US have sprung up, led by entrepreneurs who have the knowledge necessary to do so. One project undertaken by Terrapower, funded through Microsoft’s Intellectual Ventures, is trying to build a device called a travelling wave reactor. It is a little more exotic than the MSR technology from decades ago and will require considerable effort to realize. Other homegrown efforts by start-ups like Flibe Energy, Thorium Power, and Lightbridge are struggling to fund their projects without visible government support.

Flibe Energy is looking to make ends meet by exploiting the fact that LFTRs are very good at producing medical isotopes like molybdenum-99, 90% of which we currently import from Canada. Our looming medical isotope problem is irresponsible and inexcusable as these isotopes are critical to patient diagnoses and treatment. Any health care system which fails to provide for their reliable procurement will only accelerate current medical cost inflation. Transatomic is another US-based company scrapping to survive. It is now running tests using the IR-8 research reactor at the Kurchatov Institute in Moscow. Thorium Power, based outside of Washington DC, is also working with Russian scientists to use thorium fuel — not to directly generate energy, but instead to burn surplus military plutonium.

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